1. Field of the Invention
The present invention relates to a working fluid composition for a refrigerator machine and to a refrigerating machine oil. More specifically, the present invention relates to a working fluid composition for a refrigerator machine that contains a unsaturated fluorinated hydrocarbon or the like and a refrigerating machine oil, and to a refrigerating machine oil.
2. Related Background Art
In light of the problem of ozone layer depletion that has become a focus of attention in recent years, the restrictions on CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) that are used as refrigerants in conventional refrigerating machines have become more stringent, and HFCs (hydrofluorocarbons) are coming into use as substitute refrigerants.
Mineral oils or hydrocarbon oils such as alkylbenzenes have been preferred for use as refrigerating machine oils when CFCs or HCFCs are used as refrigerants, but since changing the refrigerant can cause the refrigerating machine oil used with it to exhibit unpredictable behavior in terms of its compatibility with the refrigerant, its lubricity, its dissolved viscosity with the refrigerant and its thermal and chemical stability, it has been necessary to develop different refrigerating machine oils for different refrigerants. Such refrigerating machine oils for HFC refrigerants have been developed, including polyalkylene glycols (Japanese Unexamined Patent Application Publication HEI No. 02-242888), esters (Japanese Unexamined Patent Application Publication HEI No. 03-200895), carbonic acid esters (Japanese Unexamined Patent Application Publication HEI No. 03-217495) and polyvinyl ethers (Japanese Unexamined Patent Application Publication HEI No. 06-128578).
Among HFC refrigerants, HFC-134a, R407C and R410A are routinely used as refrigerants for automobile air conditioners, refrigerators and room air conditioners. However, while these HFC refrigerants have ozone depletion potentials (ODP) of zero, their high global warming potentials (GWP) have led to their gradual restriction. It has therefore become an urgent issue to develop refrigerants as substitutes for such HFCs.
In light of this background it has been proposed to use, as substitute refrigerants for HFCs, fluoropropene refrigerants which have very low ODP and GWP, are noncombustible and are comparable or superior to HFCs in terms of their thermodynamic properties, as a measure of refrigerant performance. There has also been proposed the use of refrigerant mixtures of fluoropropene with saturated hydrofluorocarbons, C3-5 saturated hydrocarbons, dimethyl ether, carbon dioxide, bis(trifluoromethyl)sulfide or trifluoroiodomethane (see International Patent Publication No. WO2006/094303).
In addition, there have been proposed refrigerating machine oils that employ mineral oils, alkylbenzenes, poly-α-olefins, polyalkyleneglycols, monoesters, diesters, polyol esters, phthalic acid esters, alkyl ethers, ketones, carbonic acid esters, polyvinyl ethers and the like, as refrigerating machine oils that can be used with unsaturated fluorinated hydrocarbon refrigerants or refrigerant mixtures of unsaturated fluorinated hydrocarbons and saturated hydrofluorocarbons, C3-5 saturated hydrocarbons, dimethyl ether, carbon dioxide, bis(trifluoromethyl)sulfide or trifluoroiodomethane (International Patent Publication No. WO2006/094303, Japanese Patent Public Inspection No. 2006-512426 and International Patent Publication No. WO2005/103190).